1. Field of the Invention
The present invention relates to a copying apparatus provided with an auto document unit that inverts upside down recording paper with an image formed on one side thereof to return to an image forming section that forms an image on the recording paper.
2. Description of the Related Art
In order to automatically form images on both sides of recording paper (herein referred to as xe2x80x9cperform doubled-sided printingxe2x80x9d), a conventional copying apparatus is provided with auto document unit 2201 that inverts upside down the recording paper with an image formed on one side thereof to return to an image forming section that forms an image on the recording paper.
Auto document unit 2201 has, as shown in FIG. 1, intermediate tray 2205 which is provided on passage 2204 between paper cassette 2202 and image forming section 2203, and which temporarily stores recording paper with an image formed on one side thereof.
That is, recording paper 2206 is taken out of paper cassette 2202 and conveyed to image forming section 2203. An image is formed on one side of recording paper 2206 and stored once in intermediate tray 2205. When the double-sided printing of a plurality of sheets is performed on the same original, a plurality of sheets of recording paper 2206 each with the same image formed on one side thereof are temporarily stacked and stored in intermediate tray 2205.
Next, in order to record an image on the other side of recording paper 2206, recording paper 2206 is taken out of intermediate tray 2205 and conveyed again to image forming section 2203. When the double-sided printing of a plurality of sheets is performed on the same original, recording paper 2206 is sequentially taken out of intermediate tray 2205, and the same image is formed on the other side of each paper. In this way the double-sided printing is achieved.
However, there arise a problem with the configuration of the conventional example, as follows.
Namely, in the configuration of the conventional example, a plurality of sheets of recording paper 2206 each with an image formed on one side thereof are stacked and stored temporarily in intermediate tray 2205, and then another image is formed on the other side of each sheet. Therefore, it requires a considerable amount of time for recording paper 2206 to undergo the double-sided printing and to finally be discharged outside the apparatus, resulting in a disadvantage in efficiency.
It is an object of the present invention to provide a copying apparatus capable of forming images efficiently on both sides of recording paper.
That is, in the copying apparatus of the present invention, recording paper with an image on one side thereof formed in an image forming section is inserted into an auto document unit, where the recording paper is inverted upside down while intervals between a plurality of sheets of recording paper are adjusted at predetermined positions on an inverting path which is bent to form two pile-shaped upper and lower stages.